Index Value Plot (46)

http://waterwatch.usgs.gov/index.php?r=us&m=real&w=plot
The Index Value Plot above shows average rainfall in the US from 1999 to 2012. Instead of starting at an abosolute number, an index value plot uses an index which is derived from a formula using the raw data given. Once you have the index, it can be used to create a visual graph of your data in an index value plot,